Sound-emitting apparatus



S. RUBEN Apri? 7, 1931,

SOUND EM'ITTING APPARATUS Filed Aug. 16, 1929 fllillnlllllllllllllll/ Patented Apr. 7, 1931 y UNITED STATE SAMUEL RUBEN, OF NEW YORK, N. Y.

SOUND-EMITTING APPARATUS Application filed August 16, 1829. i Serial No. 386,476.

This invention relates to an improved sound emitting apparatus and more particularly it relates to a device for producing sound waves in response to fluctuations in an electriv cal current discharging through' an ionized .air gap. This is a continuation in part of my prior and co-pending application, Serial Number 550,850, iled April 8, 1922, and of m United States Letters Patent Number 1e 1, 02,951.

In the present invention, a structure is employed which' allows a continuous flow of air through the sound emitting chamber, such as a horn, with thermal changes of the air at the i l5 ionizer. This ow is obtained by means of an aspirator of the heated air type, within the expansion nozzle of which is the ionizer or cathode, the air discharge from the nozzle and therefore the aspirator capacity, being controlled by the degree of ionization which in turn in controlled by the audio frequency electrical oscillations superimposed on the direct current discharges through the cathodeanode gap. The effect of the freer air move,- ment serves to increase the amplitude of the air pulsations at the ionizer.

For a further understanding of the invention, reference is made to the accompanying drawing of one embodiment thereof in which 1 represents a heavy platinum wire cathode coated with alkaline earth oxides, such as strontium and barium monoxides. This wire is welded to nickel rod, leads l1,.,which pass throu h an insulating base 6. The cathode exten s into the nozzle of aspirator element 2, which also serves as the cooperating anode, which is supported within sound directing member 3. The cathode is connected in heating circuit 4 through the secondary coil of transformer 5, 7 being the heating current source.

i At 8 is asource of high potential direct current for ionizing the air gap between the cathode l. and the walls of aspirator 2, which serves as the anode, connected with the transformer 11, upon which circuit are applied theelectrical oscillations of audio frequencies.

At 9 the high potential circuit is connected with aspirator 2, and at 10 is a condenser. 5 The aspirator nozzle is preferably composed of a metal such as nickel chromium alloy or nickel calorized as by surface impregnation with aluminum.L

In operation, as the cathode is heated by the potential from transformer 5, there'is an 55 expansion o'f the air or gas surrounding it causing a flow of air through the aspirator; with the air expansion as it passes through the nozzle there is an air discharge up through the horn or sound directing element. When the high potential is applied, in the order of 200 to 1000 volts, dependent upon the desired volume, there is a flow of current through the gap between the cathode and the nozzle wall, the energy dissipated in the gap by the ionic current further heating the air and increasing the aspirator fiow. When audio frequency oscillations are superimposed on the ionizer circuit direct current, the ionizing current is modulated, responsive pressure changes occurring at the ionized gap and causing the sound waves to be emitted from the horn.

For higher output power for the ionization potential, a high frequency potential can be used, instead of the direct current potential,

such, for example, as a current generated by an oscillating vacuum tube at audio frequencies.

y WhatI claim is:

1. An apparatus for reproducing sound waves in a gas comprising an aspirator having nomoving part'and a member of'which isl conical in form, a sound directing body, a wall of the aspirator being employed as an anode, a cooperating cathode extending i Within the space surrounded by said anode, means for ionizing the gas between said electrodes by the discharge of a current through the,l cathode, and means for varying the vol- I uma of the gas between the electrodes by otential variations of a current at audio requency impressed upon the circuit of the electrodes.

2. An apparatus for reproducing sound Waves in a gascomprising an aspirator having no moving part and a member of which is conical in form, a wall of the aspirator being employed as an anode, a cooperating cathode extending within the space sur- W) rounded by said anode, means for ionizing the gas between the electrodes, means for varying the gas Volume between the electrodes in acoustic Vibrations by potential variations of a current at audio frequency impressed upon the cathode and anode circuit, and means for directing said acoustic vibrations.

3. An apparatus for reproducing sound waves in a gas comprising a cathode and a cooperating anode, said anode composing a portion of the wall of a conically formed body through which gas may pass freely, the said cathode extending within the space surrounded by said anode, means for ionizing the gas betweenthe electrodes, a sound directing body, and means for pulsating the gas column within said sound directing body by changes in the ionization of the contacting gas column between the electrodes responsively to electrical oscillations impressed at audio frequency upon the cathode-anode circuit.

4. An apparatus for reproducing sound waves in a gas comprising an aspirator having no moving part and a member of which is conical in form, a portion of the wall of f said member being employed as an anode, a

cooperating cathode extending withinsaid portion, means for ionizing the gas in the space between the electrodes, a sound directing body having an open passage to the space between the electrodes, and means for thermo-expansively controlling the How of gas through said ionizing space and into said passage by electrical oscillations at audio frequency impressed upon the cathode-anode circuit.

5. In an apparatus for reproducing sound waves, means for producing within a constricted area a zone of ionized gaseous medium, means acting upon the ionization producing means for causing said medium to ulsate in accordance with sound waves to e reproduced, and means for emitting sound waves from a sound directing body having an open passage to said zone.

6. In an apparatus for reproducing sound waves, a cathode filament, a cooperating anode substantially surrounding said cathode, means for ionizing the lgaseous medium within the space,separating the cathode and the anode, comprising the discharge of currentthrough said cathode, a sound directing body connecting by open passage with said space, and means for emitting sound waves in gas from the sound directing body by causing the gas in said ionization space to thermo-expansively pulsate by changes in the intensity of the ionization in response to electrical oscillations of audio frequency impressed upon the cathode-anodecircuit. i

7. An apparatus for reproducing sound waves in a gaseous medium comprising a. conduit having no moving element, a section of the wall ofsaid conduit being conductive and constituting an anode in an electrical circuit, a cooperating ilamentary cathode extending within the conduit and adjacent the anode, means for ionizing a gas column in the space between the cathode and anode by a current discharge through the cathode, means for emitting sound waves from one end of the conduit, corresponding with variations of intensity of ionization of the gas column with variations of the intensity of the ionization current in response to electrical oscillations of audio frequency impressed upon the cathode-anode circuit.

In testimony whereof, I, SAMUEL RUBEN, have signed my name to this specification this 14th day of August,rl929.

SAMUEL RUBEN. 

